The proposed work is part of an overall program in studying the biosynthesis, metabolism and function of hydroxy fatty acid sophorosides found in the yeasts Candida bogoriensis and Torulopsis species. Previous work on the purification of two glucosyltransferases from C. bogoriensis indicated that both enzymes, catalyzing the synthesis of the two glycosidic bonds in sophoroside, copurify. A major goal this year will be to utilize additional techniques of affinity chromatography and electrofocusing to purify both activities to homogeneity and establish definitely if one or two enzymes are involved. Then purification of the corresponding enzymes from Torulopsis will be attempted in order to compare the properties of the enzymes from the two species. A UDP-glucose-sterol glucosyl transferase has also been isolated from C. bogoriensis. Another goal of the project will be to isolate endogenous sterol glucosides from this organism and to determine their distribution and turnover.